In the three decades that he has been in prison, Brian Dugan has had few visitors and certainly never a celebrated Hollywood icon.

That changed this month when actor Morgan Freeman interviewed the Illinois serial killer at Stateville Correctional Center near Joliet.

Freeman attempted to plumb Dugan's mind as part of an upcoming six-part documentary for the National Geographic Channel. The series will take the Academy Award winner to remote corners of the world as he immerses himself in religious experiences and rituals, while also exploring how frontiers in neuroscience and creation intersect with traditional beliefs.

For an episode examining the concept of evil, Freeman's production company is working with neuroscientist Kent Kiehl, author of "The Psychopath Whisperer," who specializes in the use of clinical brain imaging technology to better understand major mental illnesses, with a specific focus on criminal psychopathy.

Dugan, 59, is serving a life prison sentence for three murders and a series of sexual attacks on young women who survived his violence decades ago.

Kiehl was a key witness in late 2009 when Dugan's defense team tried to persuade a DuPage County jury to spare his life for the 1983 abduction, rape and murder of 10-year-old Naperville schoolgirl Jeanine Nicarico. Two wrongly convicted men earlier spent years in prison — one on death row — for the brutal crime.

In the end, the jury meted out a death sentence for Dugan, but the verdict was commuted to life about two years later when Illinois abolished capital punishment.

Science defines a psychopath generally as an impulsive, self-centered and deceitful person lacking empathy and remorse who often engages in criminal behavior. Kiehl, whose research has included the brain scans of thousands of prison inmates, argues psychopaths such as Dugan share a defect or inactivity in an area of the brain that processes emotion, inhibition, judgment and self-control.

He first interviewed Dugan more than six years ago and found he possessed an extremely high level of psychopathy. Dugan ranked 37 out of 40 points, Kiehl said. By comparison, the average inmate's score is 25; a normal civilian rates a four.

Brian Dugan is serving a life prison sentence for three murders and a series of sexual attacks on young women.

The issue of Dugan's sanity wasn't at play because he pleaded guilty. Rather, the jury was asked through the expert testimony to consider how much ability Dugan possessed to control his savagery. Prosecutors agreed Dugan's brain is wired differently, but they argued he chose not to control himself.

Kiehl included the case in his recent book, and Hollywood soon came calling. He and Freeman interviewed Dugan on Dec. 9 at Stateville. Dugan's lawyer, Steven Greenberg, also was present. Those involved in the project either declined to comment or did not respond to interview requests.

But, in an email to state correction officials seeking access, Freeman's production team cited Dugan's candor about his "grisly and horrific actions," as reason for their interest, with the hope of offering "a glimpse into the mind of a man who has claimed he is repentant for his crimes, but also admits that if he were back in society, he is sure he'd be unable to keep himself from returning to his former life."

"Dr. Kiehl has begun to reveal how mental illness can be treated and, more importantly, caught early before it manifests as criminal behavior," wrote Brandon Fibbs, an associate producer, according to the email. "We are interested in raising awareness about the fact that there may be a way to help people like Mr. Dugan before they harm others."

After years of refusing to speak to the media, Dugan granted the Tribune a series of interviews last year. Two reporters interviewed him for about 12 hours over a three-month period.

Dugan readily admitted he is a psychopath. He acknowledged that he remains a danger to society, because of a "very strong rage," and is not rehabilitated. Yet, Dugan said, through aging and his own efforts at self-improvement, "I can remember my old self, but it's like a different person now."

He continued, "I've changed to a point, but I'm still dangerous. ... He still lives in me."

Dugan said his crimes were motivated by sexual compulsion, self-preservation and an emotional "numbness." He attributed that feeling to his drug and alcohol use, an abusive upbringing and his psychopathic nature.

"I was driven by some kind of an impulse that kept growing," he said. "It was like being a hamster on a little wheel."

He has long cooperated with mental health and other experts he said to try to understand what was wrong with him. By his own choice, Dugan said he no longer takes psychotropic or other medication for his mental issues, yet he said he would like to participate in psychotherapy to better understand himself.

"I know I'm a psychopath. I know I'm impulsive. I know I don't have much empathy. I know I used to be glib. I've improved myself on each point. I still have impulses, but they're controlled now."

A self-described atheist, Dugan said he does not believe in heaven or hell, or good and evil, which he considers simply "man-made constructions."

Dugan knows he will die in prison, which is how the families of his victims want it. They argue he is a manipulative liar, devoid of true remorse, who simply misses his time in the media spotlight.

The documentary series is set to air on the National Geographic Channel in the middle of next year.